Wearable devices are increasingly used in personal and business fields. Wearable devices generally refer to clothing and accessories that incorporate advanced computing and electronic technology. One much noted example is Google Glass, which is a type of wearable technology with an optical head-mounted display. Other types of wearable devices include smart watches, smart shirts, smart jewelry and so forth.
Users of wearable devices typically use natural language voice commands as a primary input method. However, voice commands are not practical in many scenarios. For example, users who are mute or hearing impaired are not able to use voice commands to interface with the wearable devices. In addition, it is very difficult, if not impossible, to navigate the user interface display of the wearable device by using voice commands Other navigation methods, such as a touchscreen pointer, may not be feasible due to the very small size of the user interface display.